<p>If you can just skip this particular lesson, rather than reschedule, then write him back, tell him you understand his reluctance to reschedule, and that you are willing to just cancel so as to not put him out. Then you can also ask if there is any way to get contact info from others in his studio, so that in the future you can trade with someone if necessary. But keep it short and polite.</p>
<p>The teacher's reaction might be one of a couple things:</p>
<ol>
<li><p>As you say, stress over the concerto. Or you caught him in the middle of a fight with his wife. Or whatever.</p></li>
<li><p>It's possible that several students have been cancelling or switching, and you just caught the boil over. As a teacher myself, it is incredibly frustrating to have to deal with major last minute changes because everyone seems to put their piano lesson at the bottom of the priority list. I've had weeks where not a single student came at their regular time. Although each individual student might think it was no big deal to reschedule, it was a huge headache on my part. </p></li>
<li><p>Is there any reason your teacher might be particularly ticked with you? Do you reschedule often? Last minute? Come late? Come poorly prepared? If the teacher is already feeling like you aren't taking lessons seriously enough, then he might be reaching a boiling point.</p></li>
</ol>
<p>A fourth possibility is that email can just sound a bit more abrupt and that he doesn't mean it that way. It is perfectly legitimate for him to express reluctance about rescheduling. If he has a certain schedule fairly cemented, then he may indeed have childcare arrangements, or routine plans with his family. Saying no to your request is not automatically nasty; it is his right. He doesn't owe you an explanation, but sounds like he tried to give one.</p>
<p>Because I tend to teach children rather than older students, I deal more with parents than kids on things like this, but it seems that I run about 50% every week with requests for changes and makeups. Every reason is legitimate in the parent's mind, I'm sure, but I do feel taken advantage of sometimes. And I do resent always having to be the flexible one. It doesn't seem to occur to parents to tell the tennis coach or the dentist or grandma that Tuesday at 4 will not work because you have a piano lesson then! </p>
<p>The flip side of this is, of course, that when you go out of your way to honor your commitment to the teacher, the relationship becomes valued by both.</p>
<p>Not saying this is what you're doing, just trying to offer some views from the other side.</p>