As others have said, if you are consistent in the rest of your coursework (4.0 or not), and you have significant research experience and strong letters of reference, then you can certainly get into a good PhD program. You also should apply for an REU this summer and again next summer if you don’t get one this year. Generally, the summer before your Senior year is the best for an REU because the programs use the REUs as a recruiting tool for their graduate program.
However, as you decide where to apply for graduate school, remember that the “top” schools in general terms are not necessarily the best programs for your PhD. You need to consider programs which are academically strong, which have the kind of research that you are interested in and which fit you the best. You can have a great career after your PhD even if the program is not one of those high profile ones. Your research advisor will be equally or more influential.