Anyone's toddler start having accidents out of the blue after being toilet trained for awhile?

My son is 3 and has been toilet trained for about a year. He always tells us when he has to go. However the past week or so, he's been having accidents (#1 only) in his pants once or twice per day. I ask him why and he has no explanation. I suspected an infection but he has no pain or other symptoms, and he doesn't wet the bed at night. Then I thought it was an attention thing since he has a new sibling, but she is almost 5 months old and his problem just started now. Anyone go through this and have any insight?

Re: Anyone's toddler start having accidents out of the blue after being toilet trained for awhile?

Has he been outside playing alot lately? It might be cause he is having so much fun since being cooped up over the winter???