Ew! No one could get me to use their toothbrush...! LoL
How he did it may mean something? Like if he said..oh hey there's a toothbrush in there for you now...then it may just be a practicality issue.
If he did it like my boyfriend did, it may mean more...he excitedly called to let me know he got something for me...and when I came over, he couldn't wait to show me..even saying "its your favorite color too!" Not long after, he encouraged me to bring over any things I prefer to use so for when I take a shower and stuff and cleared a shelf for me. For him, it was a huge deal cause he wanted me to know he was sharing his space with me.
A. that you stay over a lot, and B. you had better not use his.
its thoughtful from his side to think about the little things that you need or like..
He loves you! Someone loves you! Haha!
he thinks you need your own tooth brush for whatever reasons , maybe he gto annoyed you used his or someone else from his house did . that be my guess , they just want you to use your own tooth brush .