Nah, unless it involves RMT. Rude? Perhaps. Depends how it comes off. Most people would not PL someone they didn't know because they are unsure if they are just going to get mad about mouse wheel and rage quit anyway.
Honestly, just hope to get lucky finding someone plvling their own alt and ask if you can tag along. Lots of people will probably just ignore you, some will flat out tell you no, others might invite you. Regardless, don't ask multiple times, and don't sit around waiting. Have the ability to level yourself, and be happy if someone gifts you a few lvls.
Could always nicely ask in Alliance as well sometime. "New player here, anyone PLing alts and mind if I tag along?" Might get bites, might not!
If you haven't noticed in alliance chat, MGBs of the good stuff go off all the time at the DB. Those can land on all levels and last at minimum 2.5 hrs up to 4. I would certainly call that a passive form of PLing. If you're a single box, grouping with someone's trio nets them more exp (4 group bonus) even if you do nothing, so you may be able to land groups and just walk away from the game if you're up front about it.
Also, this is classic Everquest, leveling a character literally doesn't get better. There is a plethora of paths to take, mobs to kill, and adventures to go on - you out there and enjoy it! - Its the journey, not the destination.
