One of the things our counselor told my husband was that he had to be very careful about being truthful about everything, even small things. That even a little white lie will give me reason to question his character and his honesty.
That is not to say that any small white lie he tells means he's having an affair or is prone to one again, or that he's a bad guy with no character. As the betrayed spouse, I will be more sensitive to these small infractions and I have learned they can be triggers that upset me. I can't stand watching a show where someone is lying to another, even about something small. It just sends me back to the big lie that devastated me.
But back to you. I guess I don't feel I fully understand your situation well enough, nor this specific incident, to give input on whether you are reading too much into it . . . so I won't. I guess I'm just mentioning that its possible you are being overly sensitive because of what you've been through. And with good reason.