I'm writing an job application email to a smallish software company as a junior backend developer, while researching the company I stumbled upon a frontend bug,nothing website breaking. I don't know if the manager/senior dev will take that post scriptum as a show off or as a helpful tip?

I'm writing an job application email to a smallish software company as a junior back-end developer, while researching the company I stumbled upon a front-end bug,nothing website breaking. 

I don't know if the manager/senior developer will take that post scriptum as a show off or as a helpful tip?