I recall this time-frame, when virtualization was becoming the norm, yet SAP was lagging behind. If I remember correctly, the virtualization issue then was more of a support issue, rather than a licensing or contracts issue. SAP would not, until after 2009, support a production system on a virtual platform. Having said that, there are some possible issues to keep in mind.
Currently, from a contracts and licensing perspective, SAP could relate this to running an SAP system for which the metric of measurment is the number of CPU cores, where virtualizing could be seen as a method of skirting the contracted number of cores. In a virtual world, when system load reaches a certain set-point, then additional "cores" could be added quickly, then removed when the load drops below the low-water-mark, IF you were operating on a virtual platform. This could be difficult for SAP to track or prove, and thus, they will likely raise the questions, IF the older system is virtualized.
If you are operating an older release, under an older contract, which has been virtualized, this could be an issue. It is definitely something to be aware of, and to watch for. If your internal teams are not checking the internal statistics and monitoring closely, it could lead to an audit question.