Is it true that generally a person in long term therapy tends to either regress in age mentally when in sessions or to become more agressive?

T was telling me this is a normal thing that I feel like a kid when I'm around him lately. I always feel eternally 12 years old, but this is more pronounced in sessions.

I can't seem to find much info about this on the internets. I understand transference and all but is that what this is a result of? I see T as a father figure so I act like a kid more?