Well they were contractions I was having yesterday and pretty regularly but they didn't seem to be doing anything so L&D sent me home :(
sounds like it could be early labor call your doctor they may want to check you just be safe and see if you have progressed any since your last appointment
Might be contractions and you could be experiencing back labor - with back labor you may not feel any stomach pain at all.
Next time it happens keep your hands on your lower belly for a few mins and see if it becomes firm and then relaxes. If it does, you are having contractions.
Call your dr and ask if you need to come in. Since you are already at 4cm you probably need to head to l&d at the earliest sign of labor because there is a possibility of fast labor (may not happen but your cervix is quite dilated to begin with so it could happen quickly).
I say if you are concerned then go to the hospital and see what they say. Worst case scenario is they send you home.