Or are you concerned that something really dangerous happened during the first solo, which the student might forget about if you don't debrief him on the spot?
As the CFI or authorisng instructor my main concern is for your welfare and safety at all stages of the PPL course (and for me personally at any stage in your flying career but thats just me).
I have a limited amount of time on a 45 hour course to instill into you the best aviation practice and airmanship that I can and I take that task and responsibilty seriously.
That may sound like I do not subscribe to having fun also but I can assure you the two can be combined!.