Recently while I was going to Mzinchaleft to get Grimsever, I found a Glass Bow. I had the Glass smithing perk but I couldn't make one because merchants weren't selling the required materials at the time. I think I was only Level 15. I then got the Ebony Smithing perk. I was looking to upgrade but I couldn't make an Ebony Bow because merchants were not selling the required materials. I found an Ebony Bow in Drascua's (Hagraven) chest after I got the final piece of Mehrune's Razor. Around this time I was Level 20.

One thing that makes this so awkward is that I haven't found any other Glass or Ebony weapons besides these two bows. Has something similar happened to anyone else. It's like the game is reading my mind and giving me what I want.

Nope, the game just has leveled loot. If you're at a specific level, chances are that in the big chests will be something that suits your level. If you're level 5, you'll mostly find iron crap, if you're level 25 glass and ebony are possible and at level 50 you run into daedric and dragon bone/scale stuff. The smaller chests mostly contain useless things on every level.

Same goes for gold, potions and stuff. The higher level the more gold you'll find and the potions will be more powerful.

You're just lucky² be happy