Under Florida law, yes, the tow company MUST contact police, generally within 1 hour of the tow, to nofity police of the tow - so that if you call to report the vehicle stolen, the police can tell you it's not stolen, but rather, towed for a violation and they can give you the name and contact info for the tow company in question. If the bike didn't have the sticker affixed, for whatever reason, the tow company has a valid tow - even if the registration fees were paid. You wouldn't believe how many vehicles get towed because owners did things like putting the sticker in the glove compartment and forgot or neglected to actually put it ON. Those tows are still valid too for the same reason: the law requires the sticker to actually BE on there, visible, ON the tag. The way to GET the sticker is to pay the registration, but the vehicle isn't fully lawful to be on public roadways OR parked in a place visible from public view, unless it has the sticker affixed also. BOTH elements are required.
If you have reason to think your sticker was stolen (which is pretty common, especially in apartment complex lots with many vehicles), then you'll want to file a police report. But get your bike out quickly, as the storage fees are going to continue to accumulate daily and it's going to get expensive quickly. If your registration fees are current, filing the police report will do several helpful things: (a) it'll make it cheaper and easier for you to get a replacement sticker, (b) it'll enter your sticker into the NCIC system, so law enforcement will be able to identify it as stolen in case they come across it, and (c) it'll put police on notice that potential sticker theft is occurring in your area. Also, after you affix your new sticker, use something like an exacto knife to cut a slice thru it, such that it's still there, but won't come off in once piece; this makes it more difficult for someone to pull it off and makes it more likely to be spotted by law enforcement as being "not quite right" should someone try to purloin your sticker for their own use.

