HI and thanks for using the forum.
Do you still have the pain or did it go away over night? There could be a number of possible causes including a cardiac issue, chest cold, inflammation, GERD, among others. If this was a one time incident and you have not had any other symptoms, then you can wait and see if it happens again. IF it does happen again, then you should be evaluated by your doctor. If the pain is ongoing, then you need to see your doctor and have this checked out. Good luck.
Bridget
I would be checking in with my dr to see why could be nothing but never take that chance with your heart