Is it different every time, or do you always pick a guitar up and play the same thing on it?
Either way, the very first thing you will play when you pick up a guitar is a good reflection of how you feel about your guitar playing, and you'll probably find that you picked up a guitar and the first thing you played on it was very different at different times.
Is this helping you to develop as a player and take you in the direction you want to go?
I would suggest that it most probably is, because if we are conscious of this, we have greater control over it. Whatever you would normally do as a "first thing" you play when you pick up a guitar, experiment and try different things and see where they take your playing.