do you like your daycare?

I am looking for some advice. I work part time and my 9 month old son goes to an in home daycare 4 days a week. He has been there since he was 5 months old. He generally seems happy there and it's made him a more social baby and the 3 women who work there seem to really care about him. However today when I picked him up he was crying and they said he had been having a rough afternoon. He wouldn't go down for his afternoon nap and he was getting so upset she was going to call me but realized I was probably already on my way. Ultimately he had been crying on and off for 3 hours.
It's really shaken me. He seemed fine when we got home but obviously tired since he missed a nap. Is there anything I should do? Should I be worried that daycare isn't working out or should I consider this a one off and just keep an eye on things?