arrive at border

hi dears

i got tier 1 (gnrl) from india in 2011 after when i arrive to heathrow border the immigration officer ask me to some question about my application which i made from india that time i don't have the BRP card i have a only entry clearance stamp in my passport but the problem is there that officer put the arrival stamp on my visa stamp but she also wrote the four digit number on my visa stamp by hand by black pen i think that is a unusual.after that i successfully extend my tier 1G now next year i will apply for ILR
so anyone has a experience like this please advice me do i need to scare for that? do i need any special preparation?
what is that number? i am worried for this issue?

please reply and advice me.....

it is unusual, yes. however they do like to hand write stuff near entry stamps and you should start by looking for an obvious explanation

could it be that the officer's personal code did not print fully on the stamp and they decided to repeat it in pen?
could it be some faction of a date, eg month and year, of either visa issuance or your entry?
does it correspond to anything else at all in your personal data?
any portion of any reference number on your EC, flight number by which you arrived, birthday, anything?
failing that, what IS the number written?

the most usual handwritten remarks on entry stamps are either a number of a person's BRP (which you did not have) or some variant of VIPP (visa in previous passport)

thanks for reply

i check all my other data but there is no match anything with that number and arrival stam is clear readable and different number from that

still i am worrying about that