It shouldn't which is why you're results will raise alot of questions if it has thickened the lining and in such a short time. Usually when you first use it, until everything inside is rehydrated some estrogen will go systemic, but even then it's an acceptable dose. This is why progesterone is not needed with topical estrogens, even years ago with the 25mcg dose per tablet it wasn't needed and everyone was using 50mcg a week in two 25mcg doses safely. The Estring vaginal ring is 50mcg (approx) per week.
It does say on the leaflet side effects that bleeding is one of them but why? If it was from thickened lining that would be a problem so it must be caused by something else that's not a problem.