I have an A. floribunda growing in my garden, a bit over a year old, from seed.

I was pruning it the other day and collected 300 g of fresh prunings (stems and phyllodes), cooked them and now am trying to extract them to test it for DMT content.

Unfortunately I went against the "use fresh solvent" rule that applies to this kind of test / research work. I used old naptha, used previously in my MHRB and P. aquatica extractions (with freeze-precipitation) and washed with tap water. My thinking was it was ok to reuse if my intention was only to determine whether my acacia contains DMT, because whatever DMT content was left in it was not enough to freeze-precipitate, so it wouldn't precipitate again without adding more DMT; therefore, if anything would precipitate following a pull, it would have to be additional DMT pulled from the acacia.
Moreover, I added fresh solvent in roughly the same amount, so the total solvent volume was 40 ml old + 40 ml fresh = 80 ml.

I did a pull and something did precipitate. Am I correct in assuming I pulled DMT from my acacia?
The only problem is that after drying over a cold fan the white crystals dissolved and now I have a transparent liquid in the pyrex dish (liquid freebase DMT? or stray water?). I had the same problem with the phalaris extraction.
The liquid does smell like DMT though. Also the naptha taken out of the freezer was initially cloudy, but now that it has warmed up it's much clearer.

Sorry if I'm asking silly questions, I don't have much experience with DMT extractions, my focus so far has been on harmalas.

Hard to say what you've pulled, if it's from your material or residue from your solvent.

To be sure you have no DMT in your solvent you can do a backsalting.
Just dilute some vinegar with water then mix your solvent in, do few pull like that.
Things that can be left in the solvent are water insoluble (maybe tannins or other things you may have pulled before). Sorry for the approximation
The goal is to convert your freebase into salt (that are water soluble).

Water is OK to wash solvent, only for water soluble compounds (it's not the case for DMT Freebase) adding a bit of acid help converting into salt form.

Solvent washing - why product moves to water layer?

You should be better to pull second time with fresh solvent to be sure it was not a residue