Without knowing you future intentions, there's no right or wrong answer. If you have bought it for the grade number with a view to selling it in the future as you think prices are going to increase, then it is clearly an investment decision and taking it out of the slab shouldn't come into it. If you are collecting as opposed to investing, then it is entirely up to you.
I have removed many 65 & 66 graded coins from the slab to put the coins in my cabinet, some the 'finest known'. i.e The biggest number on the slab to date from that TPG. As this number doesn't translate across TPGs and in any case is not necessarily reproducible even if the same coin is submitted twice to the same TPG, I don't get too tied up agonising about removing them from the plastic. For me the question is whether the coin is an integral part of the collection, and if so, it has to fit in the tray - something slabs manifestly don't. It's horses for courses as we have discussed many times.