Husband suddenly not communicating

So I’ve been with my husband 6 years married for 2. At the very beginning we had an issue with infidelity on his part that resulted in a break up, obviously we got back together and are now happily together but we made an agreement to just be more open with each other. Just little things like communicating to each other when we go do things, not putting passwords on our phones etc. We’ve really never had any issues until recently. Over the past few weeks he has been making stops before and after work to hang out with an old friend(male) but not telling me about it until afterwards or sometimes not telling me at all. Nothing really seems suspicious because I have met this friend once and he seems nice enough but I’m just so confused why he wouldn’t just let me know since we have been communicating what we’re doing up till this point. I’m not trying to control him I have no problem with him spending time with his friend it just seems odd that he starts hanging out with this friend and suddenly doesn’t want to communicate.

I feel crazy but just needed to vent. Thanks.