iPhone 4 keeps going into recovery mode

Every other day I pick my phone up off a table and see it not responding...the first time I connected it to my computer and it told me the phone was in recovery mode; then began to download software....eventually errored out. But then I found out I could hold sleep/wake and home keys to get it to restart. I missed a few calls from the last time it did this, and I'm not sure what the problem is. I'm definitely taking it to the apple store, but wondering if anyone else is having this problem.