Blood thinners can be a systemic factor. But most of the times , poor oral hygiene, deposits are the local factors which stimulate bleeding.So get it checked

It is better to have a consultation with any nearby dentist's,,, Because gum bleeding could be because of other reasons as well like if there is any dirt or deposits present between the gums and teeth for a longer period causing gum infection, then, while brushing the teeth there might be a little amount of bleeding,, if that is the case then it could be cured by doing a good dental cleaning (scaling) of the teeth , nothing to worry,, So I suggest it will be better to get a dental checkup done ,