According to 250.501, that you can find here: http://www.thelpa.com/PA_landlord_tenant_act.pdf, if the lease term is for 1 year or less or for an indefinite term (M2M) the LL needs to give 15 days notice. If the lease term is for more than a year the notice must be 30 days. Both are from the date the notice is served.
You should reald through your lease. That is the first place to check. Not that your lease is in compliance with the law. However if you purchased it from this site or another place that advertised that you will be in compliance with your state law then you are in compliance with your specific state law.
Check in the section of your lease labled terms and see what it says.