Yes, both are clever references to themselves appearing in other media.
The first panel goes:
I’m a little nervous appearing for the first time in a while.
Eh? You appeared in a movie recently so the kids haven’t forgotten you.
It presumably refers to one of the Dragon Ball Z movies released in 2014/15.
The second panel I read as:
Your way of speaking has changed a bit since your most recent appearance in Dragon Ball.
You are a well informed person Roshi-sama.
The cutaway is from Dragon Ball Minus - a special released in 2014 that was published in Jaco the Galactic Patrolman. It includes the story of Gohan finding young Goku.
I was pleased that my Japanese is good enough now to see the difference in his way of speaking between the two examples!
I spotted the exact panel in Grandpa Gohan’s wiki page