484 PC Petty Theft at Costco California

My question involves criminal law for the state of: California

Went to Coatco in California and walked out with less than $50 worth of merchandise and got stopped by security at the exit (1-2 steps passed the guys that check your receipts and goods). I was still under the "patio" portion of the building and had not reached the parking lot yet.

Got cited for a misdemeanor ticket from the police for 484(a) PC Petty Theft and has a court date in 2 months.

Can I be (technically speaking) still considered to be inside Costco's property? If "yes" then can they still say I had stolen from them?

This is my 1st offense and I am SO SORRY and ASHAMED for what I've done. I truly am.

Yes, they can arrest you out side the building...