if you change the filter there is no chance of it being or getting blocked (in near future anyway) so if your not sure when it was done then its probably a good idea, its not a difficult job at all, just unclip to hoses and put them on the new one, make sure you get it in the right direction, and expect a little spillage (can be reduced if you take the fuel cap of for a few seconds and then put it back on, reduces the pressure in the tank), then run it for a bit to make sure it isnt leaking
