half full bottle of supplements upon opening WTH

I opened a bottle of supplements last night (I don't know if I can put the name here due to legal issues??) and had only 30 instead of 60 in there....WTH I thought, I counted because the last bottle seemed empty very fast.

Should I call the company, a lawyer (grin) or just take it back to the store? Get more, open with a video camera to proof it if there is an issue? Maybe this was a one time thing, or thousands thing where the company hopes to save money for a while......if these bottles are mechanically filled by the manufacturer, how could it be exactly at 50%???

I don't think I have a problem taking the bottle back but the issue here is why and how and who else might have been having the same problem?

God Bless