Not a problem if it happens only once in a while. The following is a reproduction of a simple explanation.

"Your emission control system actualy consists of several sub-systems, one of which is designed to prevent raw gasoline vapors from being released into the atmosphere. It does this by trapping the vapors in a charcoal-filled canister so they can be drawn into the engine and burned later when the engine is running. If you continue filling the tank beyond the normal "click-off" point you can overload the system with vapors. This can cause the engine to run "too rich" and could eventually ruin the charcoal canister."

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Reno

'93 300E 4Matic
'98 Nissan Altima
'00 Yamaha Road Star Silverado