It's not that big of a deal, but it's still pretty annoying. I let it go when it's a one-time accident. If the same person keeps doing it, acciental or not, I'll give them a look or say something about paying attention or knocking it off.
16 Gnu Swallow Tail Carver . 16 NS West . 15 NS Snowtrooper BIA
16 Burton Genesis X . 15 Now Drive
16 Flow Talon . 14 Flow Hylite