my thorlabs tube and diffuser came today , still waitin for the asians to come ... but i put the diffuser in and after i got the second set ring in all the way and put the adapter i made to go from 52mm thread to my lens mount (lens mount ring + uv filter ring) on it i looked through it and noticed a slight blemish off set from the center on the ground side of the diffuser.. it looks like a drop of sutin might of gotten on it.. should i try to clean it or send it back?