Vector pET expression vector 5738 bp

Insert : 3700 bp

transformation :Bl21 chemically competent cells .

Restriction enzymes : Not1 , Pst1

Ligation molar ratio : 1:1

after ligation & transformation i performed Miniprep & another restriction by the same enzymes

I expected to find 2 bands in the range 3700 & 5700 , but i find 2 unexpected bands 9000 bp & 3700 band

I wonder if the 9000 bands is my ligated desired plasmid why the insert band is appearing on the gell afer transformation , Miniprep ?